1. Field of the Invention
The present invention relates to a display device using self-luminous elements that emit light by application of a voltage.
2. Description of the Related Art
Display devices using self-luminous elements such as organic light-emitting electroluminescent (EL) elements have been developed. The organic electroluminescent element is a type of light-emitting diode usually called an organic light-emitting diode (OLED). The OLED emits light when carriers (electrons or holes) are injected into its light-emitting layer made of organic compounds. The OLED typically has a structure including an auxiliary layer with carrier mobility, for example, between an electrode and the light-emitting layer so that carriers are efficiently injected into the light-emitting layer during application of a voltage.
For example, a hole transport layer (HTL) and a hole injection layer (HIL), each as an auxiliary layer, are disposed between the anode and the light-emitting layer. In addition, an electron transport layer (ETL) and an electron injection layer (EIL) are disposed between the cathode and the light-emitting layer. These auxiliary layers are formed in common throughout an image display area in which a plurality of pixels are arranged, for example, by chemical vapor deposition (CVD), sputtering, or vacuum evaporation.